#if UNITY_EDITOR || UNITY_STANDALONE || UNITY_ANDROID || UNITY_WP_8_1 || UNITY_WSA || UNITY_WEBGL || UNITY_IOS || UNITY_PS4 || UNITY_SAMSUNGTV || UNITY_XBOXONE || UNITY_TIZEN || UNITY_TVOS
#define UNITY
#endif

//-----------------------------------------------------------------------
// <copyright file="HTTPRequest.cs" company="Mapbox">
//     Copyright (c) 2016 Mapbox. All rights reserved.
//     Based on http://stackoverflow.com/a/12606963 and http://wiki.unity3d.com/index.php/WebAsync
// </copyright>
//-----------------------------------------------------------------------

#if !UNITY

namespace Mapbox.Platform {


	using System;
	using System.Net;
#if !UNITY && !NETFX_CORE
	using System.Net.Cache;
#endif
	using System.IO;
	using System.Collections.Generic;
	using System.Threading;
	using System.ComponentModel;
	using Utils;
#if NETFX_CORE
	using System.Net.Http;
	using System.Linq;
#endif

	internal sealed class HTTPRequestNonThreaded : IAsyncRequest {


		public bool IsCompleted { get; private set; }


		private Action<Response> _callback;
#if !NETFX_CORE
		private HttpWebRequest _request;
#else
		private HttpClient _request;
		private CancellationTokenSource _cancellationTokenSource = new CancellationTokenSource();
#endif
#if !UNITY
		private SynchronizationContext _sync = AsyncOperationManager.SynchronizationContext;
#endif
		private int _timeOut;
		private string _requestUrl;
		private readonly string _userAgent = "mapbox-sdk-cs";


		/// <summary>
		/// 
		/// </summary>
		/// <param name="url"></param>
		/// <param name="callback"></param>
		/// <param name="timeOut">seconds</param>
		public HTTPRequestNonThreaded(string url, Action<Response> callback, int timeOut = 10) {

			IsCompleted = false;
			_callback = callback;
			_timeOut = timeOut;
			_requestUrl = url;

			setupRequest();

			Action a = () => { getResponseNonThreaded(_request, EvaluateResponse); };
			//Fire and forget ;-)
			a.BeginInvoke(a.EndInvoke, null);
		}


		private void setupRequest() {

#if !NETFX_CORE
			_request = WebRequest.Create(_requestUrl) as HttpWebRequest;
			_request.UserAgent = _userAgent;
			//_hwr.UserAgent = "Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/57.0.2987.133 Safari/537.36";
			//_hwr.CachePolicy = new RequestCachePolicy(RequestCacheLevel.NoCacheNoStore);
			_request.Credentials = CredentialCache.DefaultCredentials;
			_request.KeepAlive = true;
			_request.ProtocolVersion = HttpVersion.Version11; // improved performance

			// improved performance. 
			// ServicePointManager.DefaultConnectionLimit doesn't seem to change anything
			// set ConnectionLimit per request
			// https://msdn.microsoft.com/en-us/library/system.net.httpwebrequest(v=vs.90).aspx#Remarks
			// use a value that is 12 times the number of CPUs on the local computer
			_request.ServicePoint.ConnectionLimit = Environment.ProcessorCount * 6;

			_request.ServicePoint.UseNagleAlgorithm = true;
			_request.ServicePoint.Expect100Continue = false;
			_request.ServicePoint.MaxIdleTime = 2000;
			_request.Method = "GET";
			_request.Headers.Add(HttpRequestHeader.AcceptEncoding, "gzip,deflate");
			_request.AutomaticDecompression = DecompressionMethods.GZip | DecompressionMethods.Deflate;
			//_hwr.Timeout = timeOut * 1000; doesn't work in async calls, see below

#else
			HttpClientHandler handler = new HttpClientHandler() {
				AutomaticDecompression = DecompressionMethods.GZip | DecompressionMethods.Deflate,
				AllowAutoRedirect = true,
				UseDefaultCredentials = true

			};
			_request = new HttpClient(handler);
			_request.DefaultRequestHeaders.Add("User-Agent", _userAgent);
			_request.Timeout = TimeSpan.FromSeconds(_timeOut);

			// TODO: how to set ConnectionLimit? ServicePoint.ConnectionLimit doesn't seem to be available.
#endif

#if !UNITY && !NETFX_CORE
			// 'NoCacheNoStore' greatly reduced the number of faulty request
			// seems that .Net caching and Mapbox API don't play well together
			_request.CachePolicy = new System.Net.Cache.RequestCachePolicy(System.Net.Cache.RequestCacheLevel.NoCacheNoStore);
#endif
		}



#if NETFX_CORE
		private async void getResponseNonThreaded(HttpClient request, Action<HttpResponseMessage, Exception> gotResponse) {

			// TODO: implement a strategy similar to the full .Net one to avoid blocking of 'GetAsync()'
			// see 'Remarks' https://docs.microsoft.com/en-us/dotnet/api/system.net.http.httpclient.timeout?view=netcore-1.1#System_Net_Http_HttpClient_Timeout
			// "A Domain Name System (DNS) query may take up to 15 seconds to return or time out."

			HttpResponseMessage response = null;
			try {
				response = await request.GetAsync(_requestUrl, _cancellationTokenSource.Token);
				gotResponse(response, null);
			}
			catch (Exception ex) {
				gotResponse(response, ex);
			}

		}


		private async void EvaluateResponse(HttpResponseMessage apiResponse, Exception apiEx) {

			var response = await Response.FromWebResponse(this, apiResponse, apiEx);

			// post (async) callback back to the main/UI thread
			// Unity: SynchronizationContext doesn't do anything
			//        use the Dispatcher
#if !UNITY
			_sync.Post(delegate { callCallbackAndcleanUp(response); }, null);
#else
			UnityToolbag.Dispatcher.InvokeAsync(() => { callCallbackAndcleanUp(response); });
#endif
		}

#endif


#if !NETFX_CORE
		private void getResponseNonThreaded(HttpWebRequest request, Action<HttpWebResponse, Exception> gotResponse) {

			HttpWebResponse response = null;
			try {
				response = (HttpWebResponse)request.GetResponse();
				gotResponse(response, null);
			}
			catch (WebException wex) {
				//another place to watchout for HttpWebRequest.Abort to occur
				if (wex.Status == WebExceptionStatus.RequestCanceled) {
					gotResponse(null, wex);
				} else {
					HttpWebResponse hwr = wex.Response as HttpWebResponse;
					if (null == hwr) {
						gotResponse(null, wex);
					} else {
						gotResponse(hwr, wex);
					}
				}
			}
			catch (Exception ex) {
				gotResponse(response, ex);
			}
		}


		private void EvaluateResponse(HttpWebResponse apiResponse, Exception apiEx) {

			var response = Response.FromWebResponse(this, apiResponse, apiEx);

#if !UNITY
			// post (async) callback back to the main/UI thread
			// Unity: SynchronizationContext doesn't do anything
			//        use the Dispatcher
			_sync.Post(delegate { callCallbackAndcleanUp(response); }, null);
#else
			// Unity is playing
			if (UnityToolbag.Dispatcher._instanceExists) {
				UnityToolbag.Dispatcher.InvokeAsync(() => { callCallbackAndcleanUp(response); });
			} else { // Unity is in Edit Mode
#if UNITY_EDITOR
				Mapbox.Unity.DispatcherEditor.InvokeAsync(() => { callCallbackAndcleanUp(response); });
#endif
			}
#endif
		}
#endif


		private void callCallbackAndcleanUp(Response response) {
			_callback(response);
			IsCompleted = true;
			_callback = null;
#if NETFX_CORE
			if (null != _request) {
				_request.Dispose();
				_request = null;
			}
#endif
		}


		public void Cancel() {

#if !NETFX_CORE
			if (null != _request) {
				_request.Abort();
			}
#else
			_cancellationTokenSource.Cancel();
#endif
		}


	}
}
#endif